Pressure sensitive record material



Patented Apr. 2 i950 PRESSURE SENSITIVE RECORD MATERIAL Barrett K.Green, Dayton, Ohio, assignor to The National Cash Register Company,Dayton, Ohio, a corporation of Maryland 12 Claims.

This invention relates to improvements in pressure-sensitive recordmaterial. This application is a division of the pending application ofBarrett K. Green, Serial No. 784,938, filed November 8, 1947, forPressure-sensitive record material.

Th principal object of this invention is to provide a pressure-sensitiverecord material on which a mark of distinctive color may be produced bythe mere application of localized pressure and which is not subject tothe disadvantages inherent in the pressure-sensitive record materialdisclosed in United States Letters Patent No. 2,299,693, patentedOctober 20, 1942, on the application filed by Barrett K. Green onFebruary 23, 1940. That patent discloses a pressure-sensitive recordmaterial including the combination of an insulating medium, a rupturablesolid material such as gum dammar, having included therein intersperseddroplets of a plurality of liquid reagents, which are chemicallyreactive to produce a distinctive color in the record material at thepoints of application of localized pressure thereto, such pressurerupturing the insulating medium to permit chemical reaction between thetwo liquid reagents. The two reagents disclosed in this patent aregallic acid and ferric ammonium sulphate, each dissolved in glycerine.These reagents are ionized by the glycerine, which constitutes anionizing medium, and the chemical reaction pro ceeds by interchange ofions when the two solutions are allowed to mix, upon the rupture of theinsulat ng medium. The reaction disclosed in that patent depends uponthe presence of the reagents in an ionizing medium. However, anyavailable ionizing medium is hygroscopic, with the result that therecord material made in accordance with this patent is sensitive to anexcess of moisture, and conditions of high humidity may cause theinsulating medium to cease to be effective, with the result that thechemical reaction takes place without any application of localizedpressure, and the record material is stained and discolored, so that itceases to be useful.

As stated above, the principal object of the present invention is toprovide a pressure-sensitive record material that is not subject to thedefects and disadvantages of that disclosed in Patent No. 2,229,693, asindicated above.

Another object of the present invention i to provide a record materialupon which a mark of distinctive color may be produced, at the points ofapplication of localized pressure thereto, by such mere application oflocalized pressure, and which will not become discolored or stained due2 to the effect of light, atmospheric conditions, or aging.

In short, it is the object of this invention to provide apressure-sensitive record material in which the mark of distinctivecolor will be produced only at the points of application of localizedpressure, and at no other points, and under no other conditions.

Another object of this invention is to provide a pressure-sensitiverecord material in which the mark of distinctive color is produced bythe chemical reaction of color-forming reactants, in the absence of anyliquid ionizing medium therefor.

A further object of this invention is to provide a pressure-sensitiverecord material in which a mark of distinctive color is produced by areaction between solid particles of color-forming reactants.

Further objects, and objects relating to details and economies ofproduction, will defin tel appear from the detailed description tofollow. The objects of this invention have been attained by the severalembodiments thereof described in detail in the followin specification.This invention is clearly defined and pointed out in the appendedclaims.

In general, the present invention contemplates a pressure-sensitiverecord material comprising, in combination, a plurality of adsorptioncolorforrning reactants, such reactants being so selected that theyreact, in the absence of a liquid ionizing medium for the reactants, toform a distinctive color when brought into adsorption contact with eachother, and a solid insulating medium insulating said reactants fromcolorforming reaction contact with each other. Upon application oflocalized pressure to the record material, as by drawing a stylus acrossit, the insulating medium is ruptured at the points of ap plication ofsaid localized pressure, and such rupture permits color-forming reactioncontact between the reactants at such points, in the absence of anyliquid ionizing medium for said reactants, The result is that a mark ofdistinctive color is produced by mere application of localized pressure.

The color-forming reaction employed is of the, so-called, adsorptiontype in which an inorganic material causes a color change in an organicmaterial in adsorption contact therewith.

Of the reactant materials employed the organic material is an electrondonor aromatic compound having a double bond system which is convertibleto a more highly polarized conjugated form upon taking part in anelectron acceptor donor solid material which enhances the depth of colorper;

unit area of the record material.

In this invention, both of the color-forming material is not affected byatmospheric moisture and is relatively stable for a long period of time.Organic film-forming hydrophilic colloid substances such as gelatin,starch, methyl cellulose, or polyvinyl alcohol may be'substituted forcasein as the solid insulating medium in the record materialconstituting the embodiment of the invention. Attapulgite may besubstituted in this emreactants, as well as the insulating medium, arei.

in the solid state, and the 'eolor-form'ing-ream' tion takes place uponmere contact of solid parw.

ticles of the reactants. A pressure-sensitive record material may beprovided in which the solid particles of a plurality of color-formingreactants e are dispersed in a solid insulating medium, which insulatesthe particles from color-forming reac- I tion contact with each other.The rupture of this solid insulating -medium'by therap-plication oflocalized pressure permits the solid particles of color-formingreactants to react with each other: at the-points of application of suchpressure. to'produce the'markof distinctive color. According to thisinvention, solid particles of one of the color-forming reactants arecarried by and dispersed in a solid insulatingmedium, to which acoatingof solid-particles of another color-forming reactant is applied.

The application of localized pressure ruptures the solid insulatingmedium-at thepoints of application of such= pressure and'brings aboutcolor-forming reaction contact between the solid particles ofcolon-forming reactants at such points, thus producing the markofiidistinctive color; Preferably, this pressure-sensitive recordmaterial includes a base web, such as a fibrous webof paper or the like,towhich the coating of solid insulating medium andthe color-formingreactants is'applied.

Since it is difficultto show precisely the-spatial relationship betweenthe solid particlesof colorforming reactants, the solid insulatingmedium, and the base web, it is preferred not to attempt to illustrateany embodiment of this invention by drawings.

'In'the following examples, there will be described embodiments of thisinvention, by means of which the objects of the invention have beensuccessfully attained.

The: preferred embodiment of this invention comprises a basewebwofpaper" having applied thereto-a" coating including casein as thesolid .insulatingmedium and two colorforming reactants: "namely, kaolinand the compound 2,4 bis [-p- (p-dimethylaminophenylazo 1 anilino] 6-hydroxy sym. triazine, having the structure 0 The pressure sensitiverecord material made usingthese' ingredients is "normally yellow incolor, and the application'of localized pressure thereto, as'by drawinga stylus'across'th'e materiaL ruptures the" solid insulating medium andpermits the solid particles ofikaolin and the organic color-formingreactant to come into color-forming reaction-contact with each other,producinga dark blue mark. at the points of application of suchlocalized pressure. This record solid. insulating .medium.

record material has been made successfully, using byweight solution-ofgelatin.

a solution in toluene of about 9.5%

bodiment for the kaolin, as the inorganic material, "using gelatin orpolyvinyl alcohol as the A pressure-sensitive .the ingredients referredto above, by the follow- .ing .method: A slurry of'kaolin and water wasprepared includingioo parts by weight of kaolin to 50parts byweight ofwater and a minor proportion of a suitable dispersing agent, such assodium metaphosphate. A 29% by weight solution of casein in water wasmade, to which 5 parts icy-weight of-a 28%"ammonium-hydroxide solutionwere added; The kaolinf-slurryand this alkaline casein solution werethoroughly mixed, inthe ratio by weight of kaolin to casein of 10 to 1,and blended, and the mixture'was applied to the paper as a coating,which was dried thereon, after which the coated'paper'was calendered ortreated in any desired way to give'the proper surface finish. A solutionin' toluene'of about 0.5% by weight of the organic color-formingreactant above referred to was then applied to the coated side-of thepaper. The excess of this solution was removed and the treated paperdried to'evaporate the toluene, after which it was ready for use.

This record material has also been made using gelatin as the solidinsulating m'ediumand attapulgite as the inorganic color-formingreactant. "In this case, a slurry of attapulgite and water was made,which was'thoroughly mixed with "a 20% The proportions of attapulgiteand gelatin used should-be such that, in the finished coating, theweight ofthe gelatin will be about 20% ofthe weight of the attapulgite.The mixture of the attapulgite slurry and the gelatin solution wasapplied-to the paper as a coating, which was dried thereon; Thereafter,by weight of the organic color form ng reactant was applied to thecoated side of the paper. The excess of .this solution was'rernoved andthe treated paper dried to evaporate thetoluene'af er which it was readyfor use; The'same prccdure wassuccessfully used with a solution ofpolyvinyl alcohol substituted for the gelatin solution. The proportionsof polyvinyl alcohol and of attapulgite used where such that thefinished coating had attapulgite and polyvinyl alcohol therein in theratio byweight of 10 to 1. The methods and processes of makingpressure-sensitive record material disclosed herein are not claimed inthis application but are disclosed and claimed in the pendin applicationof Barrett K. Green, Serial No. 784,939, filed November 8, 1947,-forProcess for making pressuresensitive record material, and in thedivision thereofi'serial No. 63,212, filed'December 2, 1948.

It isuhderstood that the 'pressure sensitive record material describedherein is susceptible of considerable variation without departing fromthe spirit of the invention.

What is claimed is:

1. Pressure-sensitive record material including the combination of'asupporting member, a pluralitYoiYadsorption color-formingreactants inacoaavs sence of a liquid ionizing medium for the reactants to form adistinctive color when brought into contact with each other, disposed inproximity to each other, at least one of the reactants bein an inorganicmaterial and at least another of the reactants being an organic materialone adsorbable on the other, and a solid insulating medium, derived froman organic hydrophilic film-forming colloid substance, insulating saidreactants from color-forming reaction contact with each other, theapplication of localized pressure to the record material rupturing saidinsulating medium at the points of application of such pressure topermit color-forming reaction contact between the reactants at suchpoints, whereby a mark of distinctive color is produced by mereapplication of localized pressure, and wherein one of the coloriormingreactants is the compound 2,4 bis [p-(pdimethylaminophenylazo) anilinol6 hydroxy sym. triazine, having the structure and the inorganic reactantbeing in fine particle form providing a large adsorbent surface andwhich is an acid relative to the triazine compound so as to be anelectron acceptor when in adsorption contact with said triazinecompound.

2. The record material of claim 1 in which another color-formingreactant is kaolin.

3. The record material of claim 2 in which the solid insulating mediumis casein.

4. Pressure-sensitive record material including the combination of asupporting member, solid particles of a plurality of adsorptioncolor-forming reactants in the solid state disposed in contiguity toeach other, at least one of said reactants being an inorganic materialand at least another of said reactants being an organic materialadsorbable one on the other, and a solid insulating medium, derived froman organic hydrophilic film-forming colloid material, insulating saidsolid reactant particles from color-forming reaction contact with eachother, said reactants being so selected as to react to form adistinctive color when particles of each are brought into adsorptioncontact, the application of localized pressure to the record materialrupturing said insulating medium at the points of application of suchpressure to permit color-forming reaction contact of the solid reactantparticles at such points, whereby a mark of distinctive color isproduced by mere application of localized pressure, and wherein one ofthe color-forming reactants is the compound2,4.--bis[p-(p-dimethylaminophenylazo) anilinol 6 hydroxy sym. triazine,having the structure and the inorganic reactant being in fine particleform providing a large adsorbent surface and which is an acid relativeto the triazine compound so as to be an electron acceptor when inadsorption contact with said triazine compound.

5. The record material of claim 4 in which another color-formingreactant is kaolin.

6. The record material of claim 5 in which the solid insulating mediumis casein.

7. Pressure-sensitive record material including the combination of asupporting member, a solid insulating medium derived from an organichydrophilic film-forming colloid substance, solid particles of a firstcolor-forming reactant dispersed therein and solid particles of a secondcolor-forming reactant deposited thereon, one of said reactants being aninorganic compound and the other of said reactants being an organiccompound, one adsorbable upon the other, said solid insulating mediuminsulating said solid reactant particles from color-forming reactionadsorption contact with each other, said reactants being so selected asto react, in the solid state, to form a distinctive color when broughtinto adsorption contact with each other, the application of localizedpressure to the record material rupturing said insulating medium at thepoints of application of such pressure to permit colorforming reactionadsorption contact of the solid reactant particles at such points,whereby a mark of distinctive color is produced by mere application oflocalized pressure, said second colorforming reactant being the compound2,4 bisip- (p-dimethylaminophenylazo) anilino] B-hydroxy sym. triazine,having the structure and said first color-forming reactant being fineparticles of the inorganic material providing a large adsorbent surfacearea and which is an acid relative to the triazine compound so as to bean electron acceptor when in adsorption contact with said triazinecompound.

8. The record material of claim 7 in which the first color-formingreactant is kaolin.

9. The record material of claim 8 in which the solid insulating mediumis casein.

l0. Pressure-sensitive record material including the combination of abase web and a coating thereon, said coating including a plurality ofcolor-forming reactants in the solid state, so selected as to react byadsorption one upon another in the absence of an ionizing medium to forma distinctive color when brought into contact with each other, anddisposed in proximity to each other, at least one of the reactants beingan inorganic compound and at least another of the reactants being anorganic compound one adsorbable on the other, and a solid insulatingmedium, derived from an organic hydrophilic film-forming colloidsubstance, insulating said reactants from color-forming reactionadsorption contact with each other, the application of localizedpressure to the record material rupturing said insulating medium at thepoints of application of such pressure to permit color-forming reactioncontact between the reactants at such points, whereby a mark ofdistinctive color is: produced by mere application of localizedpressure, one of the color-forming reactants being the organic compound2,4 bis [p-(p-dimethylaminophenylazo) "anilinoi G-hydroxy symr'triazine,having the structure V and the inorganic reactant being in fine particleform to provide a large adsorbent'surface area and which is an acidrelative to the organic compound-so. astobean electron acceptor when inadsorptioncontact with said organic compound.

' REFERENCES CITED The following references are of record in the file.of this patent: 10

1 FOREIGN PATENTS Country Date Great'Britain Jan. 4', 1943 Number

1. PRESSURE-SENSITIVE RECORD MATERIAL INCLUDING THE COMBINATION OF ASUPPORTING MEMBER, A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS INTHE SOLID STATE, SO SELECTED AS TO REACT IN THE ABSENCE OF A LIQUIDIONIZING MEDIUM FOR THE REACTANTS TO FORM A DISTINCTIVE COLOR WHENBROUGHT INTO CONTACT WITH EACH OTHER, DISPOSED IN PROXIMITY TO EACHOTHER, AT LEAST ONE OF THE REACTANTS BEING AN INORGANIC MATERIAL AND ATLEAST ANOTHER OF THE REACTANTS BEING AN ORGANIC MATERIAL ONE ADSORBABLEON THE OTHER, AND A SOLID INSULATING MEDIUM, DERIVED FROM AN ORGANICHYDROPHILIC FILM-FORMING COLLOID SUBSTANCE, INSULATING SAID REACTANTSFROM COLOR-FORMING REACTION CONTACT WITH EACH OTHER, THE APPLICATION OFLOCALIZED PRESSURE TO THE RECORD MATERIAL RUPTURING SAID INSULATINGMEDIUM AT THE POINTS OF APPLICATION OF SUCH PRESSURE TO PERMITCOLOR-FORMING REACTION CONTACT BETWEEN THE REACTANTS AT SUCH POINTS,WHEREBY A MARK OF DISTINCTIVE COLOR IS PRODUCED BY MERE APPLICATION OFLOCALIZED PRESSURE, AND WHEREIN ONE OF THE COLORFORMING REACTANTS IS THECOMPOUND 2,4 BIS (P-(PDIMETHYLAMINOPHENYLAZO) ANILINO) 6 - HYDROXY SYM.TRIAZINE, HAVING THE STRUCTURE.